feat: add TUnit.Logging.Microsoft package and shared web app logging

[thomhurst]

Summary

• New TUnit.Logging.Microsoft package — provides Microsoft.Extensions.Logging integration without ASP.NET Core dependencies, enabling ILogger output capture in TUnit test output for any IHost or generic DI scenario
• Shared WebApplicationFactory logging — adds TUnitTestIdHandler (client-side header propagation) and CorrelatedTUnitLoggerProvider + TUnitTestContextMiddleware (server-side per-request test context resolution) so a single shared web app can route logs to the correct test
• Improved log routing — logs now write directly to TestContext.Output.WriteLine()/WriteError() instead of Console.WriteLine, and error-level logs are properly separated

New package: TUnit.Logging.Microsoft

• TUnitLogger / TUnitLoggerProvider — writes directly to test context output
• ILoggingBuilder.AddTUnit(context) and IServiceCollection.AddTUnitLogging(context) extension methods
• No ASP.NET Core dependency — works with any IHost-based app

Shared web app support in TUnit.AspNetCore

• TUnitTestIdHandler — DelegatingHandler that propagates TestContext.Id via X-TUnit-TestId header
• TUnitTestContextMiddleware — extracts test ID from request headers and resolves TestContext via GetById()
• CorrelatedTUnitLogger — resolves test context per log call (HttpContext items → AsyncLocal fallback → no-op)
• IServiceCollection.AddCorrelatedTUnitLogging() — one-call registration with IStartupFilter
• WebApplicationFactory<T>.CreateClientWithTestContext() — convenience extension

Breaking changes

• TUnitAspNetLogger, TUnitLoggerProvider, TUnitLoggerScope removed from TUnit.AspNetCore.Logging namespace (replaced by TUnit.Logging.Microsoft types)
• Extension methods (AddTUnit, AddTUnitLogging) remain API-compatible in TUnit.AspNetCore.Extensions

Test plan

• dotnet build TUnit.Logging.Microsoft — all 3 TFMs (net8.0/net9.0/net10.0) compile cleanly
• dotnet build TUnit.AspNetCore — all 3 TFMs compile cleanly
• dotnet test TUnit.AspNetCore.Analyzers.Tests — net8.0/net9.0 pass (net10.0 failures are pre-existing System.Runtime version mismatches)
• Manual smoke test: AddTUnitLogging(testContext) captures ILogger output in test results
• Manual smoke test: AddCorrelatedTUnitLogging() + CreateClientWithTestContext() routes shared app logs to correct test

🤖 Generated with Claude Code

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

This PR introduces a well-structured logging abstraction:

• The new TUnit.Logging.Microsoft package successfully decouples logging from ASP.NET Core dependencies
• The correlated logging architecture (header propagation → middleware extraction → context resolution) is sound and enables the shared WebApplicationFactory scenario
• All CLAUDE.md mandatory rules are satisfied (no VSTest dependencies, proper async patterns, AOT compatibility)
• Code follows modern C# conventions and patterns

The approach of separating generic IHost-compatible logging into its own package while building ASP.NET-specific correlation on top is a good architectural decision.